Filter cleaning apparatus



April 25, 1967 J. F. KING, JR 3,315,446

FILTER CLEANING APPARATUS Filed July 15, 1963 6 Sheets-Sheet l fas-April 25, 1967 J. F. KING, JR

FILTER CLEANING APPARATUS Filed July 15, 1963 6 Sheets-Sheet 2 April 25,1967 J. F. KING, JR

FILTER CLEANING APPARATUS 6 Sheets-Shee t Filed July 15, 1963 ZNVENTORefameslfi z lgg eh ATToRNEYs' BY J April 25, 1967 J. F. KING, JR

FILTER CLEANING APPARATUS 6 Sheets-Sheet 4 Filed July 15, 1965 INVENTORefames I? ATTORNEYS April 25, 1967 J. F. KING, JR

FILTER CLEANING APPARATUS 6 Sheets-Sheet 5 Filed July 15, 1963 A ril 25,1967 J. F. KING, JR 3,315,446

FILTER CLEANING APPARATUS Filed July 15, 1963 6 Sheets-Sheet 6 INVENTORJkmes I (/12 ATTORNEYS United States Patent 3,315,446 FILTER CLEANINGAPPARATUS James F. King, Jr., Winston-Salem, N.C., assignor to TheBahnson Company, Winston-Salem, N.C., a corporation of North CarolinaFiled July 15, 1963, Ser. No. 294,880 7 Claims. (Cl. 55-272) The presentinvention relates in general to filter apparatus, and more particularlyto automatically cleaned filter apparatus for removing selected types ofsolid foreign matter from a fluid medium. This invention has particularapplication to the removal of lint fibers from lint-laden air and willbe described in connection with that specific application, although itwill be understood that the invention will provide advantageousoperating characteristics in many other applications.

It is common practice in textile processing plants to provide continuousconditioning of the air in such plants so as to maintain suchtemperature and humidity conditions as will insure that the textilefibers being processed are in the optimum condition for the processingbeing performed. Such textile air conditioning involves moving of largequantities of lint-laden air, since it is an inescapable incident ofhigh speed textile processing that lint fly is dislodged from thetextile yarn or fabric and becomes entrained in the air streams movingabout the building. Thus lint screening becomes necessary to remove thefibers from the air to be conditioned and thereby protectlint-vulnerable mechanical components downstream from the lint screen.Because of the high concentration of lint in textile room air, the lintaccumulation on a lint screen occurs at a speed rate that requiresperiodic screen cleaning to prevent plugging of the air passages in thescreen and resultant faulty operation. Considerable effort has thereforebeen devoted to the provision of automatically cleaned screens whichwill effectively remove the lint from the air at sufficiently frequentintervals and in an appropriate manner to maintain the air in thetextile processing spaces in appropriate condition. It will be apparentthat it is impractical in such textile air conditioning installations tocontinuously condition fresh supplies of exterior ambient air anddeliver the same to the textile processing space, for example a textilespinning room, at a suflicient rate to provide rapid changing of the airin the processing space, as excessively expensive temperatureconditioning, air cleaning and humidifying apparatus will be required.

The common practice, therefore, is to provide a facility forconditioning and recirculation of the air in the processing space, suchas an apparatus room adjoining the textile processing room into whichair from the rocessing room is withdrawn for cleaning and conditioningand then circulated back to the processing room. Several types of filtermechanisms have been heretofore employed to remove lint from the airWithdrawn into the apparatus room or to remove lint from the air atselected zones in the processing room. One of these types of filterapparatus heretofore employed has been the brush and wiper dotted rotarydrum, wherein a drum shaped screen was rotated past a brush structurewhich served to mechanically sweep the lint fibers from the surface ofthe screen drum and effect discharge of the fibers to a suitablecollection zone. Such devices had undesirable characteristics as theyreleased great quantities of fine dust into the return air which wouldimpede or interfere with further processing of the air, and involvedrotation of the greatest mass part of the apparatus, namely the screen.Further, such apparatus, wherein one end of the drum was open, requireda circumferential seal which absorbed a great amount of power andrequired more flexibility than could be easily achieved because the openend of the drum could not be kept precisely round when produced by massproduction methods.

Another type of automatically cleaned filted developed for suchprocesses involved a flat screen of large area appropriate to the volumeof air to be handled wherein a wiping blade spanning the small dimensionof the screen was scanned back and forth along the length of the longdimension of the screen by a chain drive to dislodge the lint from theclean surface and effect its discharge to a collection point below thescreen. Such flat screen type filter mechanisms also had undesirableproperties, as the long-span chain drive was subject to lintcontamination and could not be effectively kept clean, the mechanicalwiping of the screen disturbed the lint mass on the surface of thescreen and allowed the dust which had been eifectively filtered out ofthe air to then pass through the screen, a very heavy screen frame wasrequired because of the air load imposed on the surface of the screendue to the static pressure difference existing across the filtersurface, and, in practice, sagging of the central portion of the screenbecame unavoidable and rendered exceedingly diflicult attainment ofrelatively uniform effective wiping action over all parts of the screenarea.

To overcome these disadvantages, others have commercially offeredautomatically dotted screens utilizing a moving filter paper cover forthe screen which is rolled across the screen and continuously orperiodically changed at a sufficient rate to prevent contamination ofthe portion in the air stream. Such devices, however, have the drawbackof high replacement cost of the paper medium.

An object of the present invention, therefore, is the provision of anovel filter apparatus having an automatically cleaned screen, whichavoids the aforementioned disadvantages of prior art filter apparatus.

Another object of the present invention is the provision of a novelfilter apparatus wherein large area screen capacity is provided in asmall space and wherein the screen is pneumatically stripped of lintfibers or similar foreign matter in a manner minimizing release of dustinto the air and which attains substantially complete stripping of thescreen in one pass over the screen surface.

Another object of the present invention is the provision of a novelfilter apparatus having an automatically pneumatically doffed screen,wherein the screen is not subject to deformation from air loads, and maybe used with many different types of filter fabrics.

Another object of the present invention is the provision of a novelfilter apparatus for removing lint fibers from lint-laden air, andsimilar applications, wherein the filter apparatus may be constructed instandardized modules of selected capacity by mass production techniques,to be adaptable for use as single filter units located at selected zonesin or associated with an area to be served or in a multiple unitinstallation of varying numbers of units for a central station returnair filtering application, and wherein substantially no more suctionsystem is required to handle a large number of such units or centralstation bank of the filters than would be required to operate one filterunit. Such a standardized module filter unit suitable for such variedinstallation situations has great flexibility, permitting the units tobe assembled in central station groups of large air handling capacity orto be installed in spaced single unit arrangements, for example overinlets to ducts leading from selected locations about a room where lintfly problems are encountered, or in building wall openings leading fromsuch a room to other rooms or to outside air, or in hoods overlyingcertain types of machinery responsible for producing such lint flyproblems, such as high speed carding engines and the like.

Other objects, advantages and capabilities of the present invention willbecome apparent from the following 7 ing the present invention isemployed;

FIGURE 2 is an elevation view of such a central station bank of filterunits as viewed from the line 22 of FIGURE 1;

FIGURE 3 is a rear elevation view to enlarged scale,

of a filter apparatus module embodying the present invention, viewedfrom the downstream side;

FIGURE 4 is a vertical section'view of the filter apparatus module,taken along the line 44 of FIGURE 3;

FIGURE 5 is an enlarged section view illustrating the FIGURE 7 is afragmentary section view illustrating the action of the stop mechanismfor the suction stripper tube, taken along the line 77 of FIGURE 4;

FIGURE 8 is a' diagrammatic view of an exemplary control system for aplurality of filter modules of the present invention;

FIGURE 9 is a fragmentary section view of a modified filter unitconstruction taken from a position corresponding to the line 44 ofFIGURE'3, with part of the atmospheric valve broken away;

FIGURE 10 is a fragmentary rear elevation view of a the structure shownin FIGURE 9; and

w FIGURE 11 is a vertical section view taken along the line 11 11 ofFIGURE 10.

The invention will be specifically described in connection with acentral station filter bank for a textile spinning room installation,from which description an adequate understanding of the invention willbe attained to enable persons skilled in the art to use the invention inthe many other applications for which it is suitable. Referring to thedrawings, wherein like reference characters designate correspondingparts throughout the several figures, and particularly to FIGURES 1 and2 illustrating an exemplary installation involving the present inventionto remove lint fibers from lint-laden return air in a textile spinningroom air conditioning system, the reference character 12 designates atextile spinning room containing, forexample, a large number of textilespinning frames (not shown), the surrounding air of which is to becontinuously conditioned during operation of the spinning frame tomaintain desired temperature and humidity conditions. In this exemplaryinstallation, an apparatus room 13 adjoins the spinning room 12 andcontains the usual air treating and conditioning apparatus, indicatedgenerally at 13a, and an air circulating fan 13b which effects return ofair through suitable return ducts of a return grill 14 from the spinningroom 12 into the apparatus room 13 and through treating and conditioningapparatus 13a, and discharges the treated and conditioned air throughsuitable ducting or a supply opening 15 in the illustrated installation.A central station filter bank is provided at 16 in the form of apartition spanning the apparatus'room 13 from side to side and from topto bottom in the path of the return air from the spinning room 12 to theair treating and conditioning apparatus 13. It will be understood bythose skilled in the art that the filter bank 16, which is made up of aselected number of modular filter units 17 constructed in accord-' ancewith the present invention will not necessarily have its total areaoccupied by such modular filter units 17,

but will embody only an' appropriate number of such filter units 17 aswill be adequate to handle the volume of air being circulated throughthe system. For example, if sixteen of such modular filter units 17 arerequired for the particular air volume rate encountered in theinstallation, the modular filter 'units 17 may conveniently be arrangedin four vertically extending tiers of four modular units each, arrangedin sideby side relation in the central portion of the partition betweenvertical channel posts 18, with the remaining portion of the partitionclosed by blank plates 19 flanking the group of filter units 17 andextending to the opposite walls of the apparatus room 11.

Each modular filter unit 17 is constructed with a rectangular base 20,formed for example, of sixteen gauge steel having a square periphery andan angle flange 21 at each of the four edges thereof. In the center ofthe base 2!) is a large diameter hole 22 bounded by a circular flange23, to which is spot welded a screen drum generally I indicated by 24having a perforated cylindrical wall 25 whose downstream edge liesradially outwardly of the circular flange 23 and laps the same. To theopposite edge of the cylindrical screen wall 25 is welded a drum head 26formed, for example, of 22 gauge. sheet metal having radially extendingstiffening. spokes 27 pressed therein and a formed angle flange 28around its outer edge which is pressed over the cylindrical screen wall25 and spot welded thereto. The screen wall 25 is formed at onecircumferential location thereon with a locking channel 29 which spansthe axial length of the screen wall 25 to facilitate removeablelocking'of a filter medium in a outwardly covering relation to thescreen wall 25 as will i be later described. This locking channel 29 maybe conventionally formed by a U-shaped channel member 30 having oppositeprojecting flanges 31 at the ends of the. channel sides adjoining thechannel opening which arespot welded to the opposite edges of the rolledscreen wall 7 25 as shown more clearly in FIGURE 6. 1

In one practical example, the base 20 may be formed as a 41" squarehaving a 36" diameter hole 22 therein, and the screen wall 25 may berolled into a 26" diameter screen having a 15" wide open area with /2"selvedge on each side, the perforations in the screen wall 25 having adiameter of for example, /2" with the perforations ar-.

ranged in staggered rows so that the open area of the clearly shown inFIGURE 5 into which a circular extru- I sion'33 of a bearing housing 34,for example of cast aluminium, extends. The bearing housing 34 includesa mounting Wall 35 which lies flatagainst the filter'drum.

head 26 and is suitably fixed thereto and axially projecting bodyportion 36 extending toward the base 20 and terminating in an outwardlyspaced wall portion 37generally parallelling the plane of the mountingwall 35. Each of the walls 35 and 37 have axially aligned hearingassemblies for journalling a rotating stripper tube unit 38 and includeopenings 39, 40 surrounded by, bosses having axially elongatedcylindrical surfaces against which sleeve bearings 41 and 42 are seated.The sleeve bearing 41 ro-- tates freely against the surface of opening39 and is suitably held, as by a retaining washer 43 and split ring 43on a bearing seat of one arm 44 of a cast aluminum elbow 45 forming partof the stripper tube unit 38. The elbow includes an arm 46 extending atright angles to the arm 44 and a bore 47 extending entirelytherethrough. A short journal tube 48 having a length correspondingsubstantially to the axial length of the bearing housing 34 has one end48a tightly fitted and suitably fixed in the bore 47 of the elbow arm 44and is rotatably journalled at its other end in the sleeve bearing 42. Asuitable felt seal 49 in the bearing housing 34 and adjoining the sleevebearing 42 is in sealing engagement with the exterior of the journaltube 48. A fixed elbow 50 having a bore 51 in registry with the end 48bof the tube 48 and a suction tube 52 fixed in the opposite end of thebore 51 extends from the elbow 50 to suitable suction sources.

The arm 46 of the rotating elbow 45 which lies externally of the screendrum 24 adjacent the drum head 26 supports a radial tubular leg 54 fixedto the elbow arm 46 in communication with the bore 47, the outer end ofWhich is joined to a pneumatic stripping tube 55 lying immediatelyexternally of the screen wall 25 in parallelism with the axis of thescreen wall and adapted to travel circumferencially one complete turnabout the screen wall surface. The stripping tube 55 is also in the formof a hollow tube which is closed at its end adjacent the base and has anintake slot 56 extending subtsantially the length thereof facing towardthe screen Wall flanked by suitable lips, formed for example by aplastic stripper tube nozzle 57. ably counterbalanced by a counterweight58 carried by the rotating elbow 45.

A suction seal and filter medium retainer 59 is designed to co-act withthe locking channel 29 to seal the stripper tube nozzle 57 againstambient air pressure when the stripper tube is at its normal orquiescent position, and to this end is formed of a suitable resilientlydeformable material, such as vinyl plastic extrusion, shaped asillustrated in FIGURE 6 to provide a locking tongue portion 60 having,for example, saw-tooth cross sectioned ribs on the opposite sidesthereof and a hollow sealing head portion 61 provided with a thinupwardly arching top web 61a. When an endless strip of filter medium,indicated by the reference character 62, or the opposite edge portionsof a cut strip of filter medium, is pressed into the channel member 30after the filter medium has been placed about the screen wall 25, thetongue 60 of the retainer 59 is pressed into the opening of the channelmember 30 and acts to draw the filter medium taut over the surface ofthe screen wall 25 and locks the same within the channel member 30.Also, this retainer 59 serves to seal the stripper tube nozzle 57 closedwhen the stripper tube 55 overlies the retainer 59, as the suctionconditions at the nozzle 57 draw the upwardly arched web 61a of theretainer head 61 into intimate sealing contact with the suction nozzlelips along the entire length thereof.

The rotating stripper unit 38, is driven by means of a small aircylinder 65 fixedly supported by the bearing housing 34 and having, forexample, a 6" stroke. The air cylinder 65 is of the type having athrough piston rod wherein piston rod sections 66a and 66b projectexternally from the opposite ends of the air cylinder 65. The outer endsof the piston rod sections 66a, 66b are fixed to the de pending to legs67a, 67a of a drive yoke 68 whose web 69 slides in a suitable guidewayin the bearing housing 34. Also, a drive cable 70 having a full turnabout the exterior of the tubular section 48 extends between thedepending legs 67 of the drive yoke 68 and is suitably anchored theretoby spring anchors 71 maintaining proper tension on the drive cable 70.The spring anchor 71 may, for example, comprise a spring stop washer 71fitted over the adjacent end of the drive cable 70 having acircumferential rabbet for receiving the outermost turn of a coil spring72 and a suitable cable clamping bushing or sleeve 71" backing up thewasher 71'.

A stop mechanism illustrated in detail in FIGURE 7 and located on thedrum head 26 is provided adjacent the end of the retainer 59 and lockingchannel 29 to accurately locate the stripper tube 55 over the retainer59 at the rest position and provide a full 360 range of rotation for thestripper tube 55. This stop mechanism comprises a stop lever 73pivotally secured, as indicated at 74, to the drum head 26 and having abody portion 73a overlying the drum head 26 and an ofiset terminalportion 73b lying The rotating stripper tube unit 38 is suitin a planeparallelling the plane of the body portion 73a and spaced toward thebase 20, which is connected to the body portion 73a by a connecting Web730 forming a shoulder to abut against the periphery of the drum head.The offset terminal portion 73b of the stop lever 73 projects into thepath of the stripper tube 55 to be engaged by the latter and shifted toeither the solid line position or the broken line position illustratedin FIG- URE 7. The shoulder formed by the connecting web 73c is solocated relative to the pivot 74 that the stop lever 73 will be stoppedby engagement of the shoulder with the drum head periphery when thestripper tube 55 is properly centered over the retainer 59, regardlessof the direction of travel of the stripper tube 55.

A suitable hanger bracket 75, illustrated as having an L-shapedconfiguration, is fixed to the air cylinder 65 and has a depending leg75a carrying a normally closed threeway air valve 76 which is actuatedby contact button 76:: positioned to be engaged by one of the dependinglegs 67a of the drive yoke 68. The arrangement is such that the valve 76is in a closed position relative to its upstream port and vents itsdownstream port to atmospheric pressure at all times except when thedrive yoke 68 is at its limit of travel illustrated in FIGURE 3 whereinthe depending leg 67a of the drive yoke engages and forces inwardly thevalve contact button 76a.

An exemplary control layout for a plurality of filter units of theforegoing construction is illustrated in FIG- URE 8, wherein threefilter units are indicated generally by broken lines and designated bythe reference characters 17a, 17b, 17c, each including an air cylinder65 having chambers 65:: and 65b at the opposite sides of the piston, andhaving an air valve 76. The cylinder 65 and air valve 76 of each filterunit are shown in solid lines for clarity of illustration. Fluid supplylines to the left hand filter chamber 651) of each filter unit 17a, 17b,170 are indicated by the reference character 80a, 80b, 80c and connectin parallel with a fluid supply manifold line 81 extending to one portof a four-way valve 82, for example, a solenoid valve controlled by asuitable timer 83 of conventional construction. The four-way valve 82,as is the conventional practice, has an exhaust port 84, a main fluidsupply port 85 connected with a suitable source of fluid under pressure,and a fourth port connected to a fluid supply line 86 communicating withand forming the supply to the right hand cylinder chamber 65a ofcylinder 65 in the filter unit 17a. Assuming that all filter units17a17c are initially at a rest position wherein the drive yoke 68 isfully thrown to the right, as viewed in FIGURE 3, with the dependingyoke leg 67a spaced fartherest from the air valve 76, the timer 83causes suction to be applied to the suction tubes 52 in a conventionalmanner and applies pressure to the port 85. Application of fluidpressure, for example air pressure, to the main inlet port 85 of thefour-way valve 82 routes air pressure to the fluid line 86 connected tothe drive cylinder chamber 65a of the first filter unit 17a, while theother drive cylinder chamber 65b is connected through line 80a, 81 andthe solenoid valve 82 to the exhaust port 64. Thus the piston of drivecylinder 65 of the first filter unit 17a will be activated to shift thedrive yoke 68 through a full advance stroke toward the left, as viewedin FIGURE 3, carrying therewith the drive cable 70 and rotating thestripper unit 38 so as to sweep the stripper tube 55 through a 360 pathalong the exterior surface of the screen wall 25 and filter medium 62thereon to pneumatically clean lint and dust from the exterior surfaceof the filter medium and withdraw the same by pneumatic suction throughthe suction tube 52. The sweep of the stripper tube 55 will be stoppeddirectly over the retainer 59 by the stop lever 73 as previouslydescribed, and the depending leg 67a of the drive yoke 68 at the end ofthe stroke will engage the contact button 76a of the valve 76 and forcethe same to open position. This opening of the valve 76 asso- V ciatedwith the first filter unit 17a connects its upstream port with itsdownstream port and cuts oil the external vent to atmosphere, thusadmitting the pneumatic pressure from the line 86 to which the upstreamport of the valve 76 is connected, through a fluid supply line 87connected to the downstream port of valve 76 and to the correspondingdrive cylinder chamber 65a of the next filter unit 17b. The air cylinder65 of the second filter unit 17!) will be activated in similar manner tothe air cylinder of the first filter unit 170, and upon completion ofthe advance stroke of the associated drive yoke 68, the normally closedair valve 76 of the second filter unit 1717 will be opened admittingpneumatic pressure through line 88 to the cylinder chamber 65a of thethird filter unit 170, producing a similar cycle of operation.

When all of the filter units of the central station bank of filter unitshave been driven through their advance 7 7 stroke, the timer 83 thenshifts the four-way valve 82 the timermay cut 011 the suction supply tosuction tubes 52 by suitable conventional valve means or the suction tothe suction tubes 52 may be left on during the return strokes of tubes52, as desired.

As the pressure applied to cylinder chamber 65b of filter unit 17adrives the yoke arm 67a on of contact button 76a of valve 76, the valve76 returns by internal spring bias to closed condition venting thedownstream port connected to branch 87 to atmosphere, and thuspermitting the pressure through line 80b to chamber 65b of filter unit17b to drive the latter in return direction. The cylinder 65 01 thethird filter unit 170 and any subsequent units are activated throughtheir return cycle in like manner.Thus, the stripper tube units 38 ofall of the filter units are rotated through their return strokes insubstantially concurrent manner, although there is a slight timestaggering of the initiation of return of the successive filter units.Since the stripper tube 55 of only one filter unit is displaced off ofits associated suction seal and retainer 59 at any one time during theadvance stroke, all of the other stripper tubes being sealed by theirassociated retainers 59 except during their individual sweeping cycle,the pneumatic doffing suction system connected to the suction tubes 52of the plurality of filter units does not have to provide any greatersuction than would be needed for a single filter unit.

It will be apparent, of course, that by providinga similar valve andvalve actuation arrangement for regulating the return stroke as isprovided for controlling the advance stroke, and maintaining fullsuction pressure on the stripper tubes during the return stroke, thestripper units may be caused to pneumatically doff the filter media ofthe filter units during the return stroke as well as the advance stroke.

An alternate arrangement for conditioning the stripper units 38 toextinguish the suction currents at the nozzle 57 when the associatedstripper tube 55 occupies its rest position and prevent it from loadingthe master suction source, is illustrated in FIGURES 9, 10 and 11. Inthis modification, the filter unit is of the same construction as thatdescribed in connection with the first embodiment, except that the thindeformable top web 61a is omitted from the filter medium retainer 59 anda valve "is associated with the suction tube 52 at the bearing Q o beras the tongue portion is forced into the channel 29. Valving of thesuction pressure through suction tube 52 to stripper tube 55 isaccomplished by a valve assembly which is substituted for the elbow 50and mounted on the bearing housing 34. The valve assembly 90 comprises acast valve housing 91 provided with an internal chamber 92 with whichthe suction tube 52 communicates.

A short tube section 93 is pressed into an opening of the valve housing91 and conforms to the journal tube 48 in the bearing housing 34 toregister therewith and form a continuation thereof. The end of the tubesection 93 lying within the chamber 92 forms a surface on which a valvemember 94 can adequately seal, the valve member 94 being formed of adisk of suitable sealing'material, such as a fiber. washer or pad,bonded onto a metal hinge panel 95 pivoted about a hinge axis 96. A yoke97 is securely fixed to hinge panel 95 and is pinned to a link 98 whichis secured to a backing plate 99 supporting the free end of a bellows101. The opposite end of the bellows 101 is fixed to the valve housing91 and is covered by a retaining cap 102 having an extension 103 alignedwith the axis of the bellows 101. A spring anchor 104 is attached to thebacking plate 99 by a suitable fastener screw 104a and a return spring'105 is connected to the spring anchor 104 and extends through thebellows 101 An atmospheric valve.107 communicating with the in-.

terior of the bellows 101 through tube 108 selectively vents the bellowsinterior to atmosphere or isolates the sameand permits suction pressureto build up therein through the leak port in screw 104a, in accordancewith the position of the drive yoke 68 and piston rods 66a, 66b. Thevalve 107 is mounted on the filter drum head 26 just above the web 69 ofdrive yoke 68 in a position to be contacted by either of two actuatorpins 109, 109 fixed on the yoke 68 at proper locations to strike thevalve 107 slightly before the strokes of the yoke 68 are I completed.The valve 107 includes a hollow'valve body 110 fixed to the drum head 26having an outlet 111 connected by tube 108 to the bellows interior, anda rigid extension 112 having a valve plate 113 which is normally heldtightly against valve seat 114 by a spring 115. When one of the pins109, 109 strikes the valve extension 112,

i the valve plate 113 is rocked away from its seat 114, thus venting theinside of the valve bodygllt) and of bellows 101 communicating therewithto atmosphere. When the a 0 interior of the bellows 101 is thus ventedto asmosphere and atmospheric pressure conditions are attained therein,the pressure in the bellows then exceeds the suction pressure conditionsin the valve chamber 92 established through tube 52 and the bellows 101expands against the force of spring to the position shown in FIGURE 11,

.closing the valve hinge. panel 95 against tube 93 and preventingcommunication of suction pressure from tube 52 to stripper tube 55.

It will be apparent that when the piston of air cylinder 65 of theassociated filter unit has completed its stroke in either direction,either pin 109 or 109 on the drive yoke 68 will have contactedtheatmospheric valve extension 112 and rocked the valve plate 113 awayfrom its seat 114, thus venting the inerior of valve body and bellows101 to atmosphere and producing a much greater pressure in the bellows101 than the suction pressure in valve chamber 92, so that the bellows101 expands and closes the valve member 94 against the seat formed bythe adjacent end of tube 93. This is the condition attained in valveassembly 90 when the stripper tube 55 occupies its rest position. Whenthe air cylinder 65 is next activated to drive the yoke 68 and rotatethe stripper unit, slight movement of the yoke 68 withdraws the pin 109or 109' from contact with the valve extension 112 and permits theatmospheric valve 107 to close under the biasing force of spring115.Pressures will very quickly equalize between the inside and outside ofbellows 101 due to leakage through the leak port of screw 104a, so thatreturn spring 105 can collapse the bellows 101 and open valve member 94to communicate suction pressure from tube 32 to stripper tube 55 andeffect pneumatic dofling during the remainder of the rotary stroke ofthe stripper unit. When the stripper tube 55 nears the completion of itsone revolution stroke, one of the pins 109, 109 again engages theatmospheric valve extension 112 and rocks the valve 107 to opencondition, to vent the bellows interior to atmosphere and shift thevalve member 104 to closed condition as described above. Thus, by thisvalving arrangement, the stripper tube 55 is cut off from the suctionpressure source whenever it attains its rest position until it is againdisplaced from the position, to attain the action and characteristics ofthe first described embodiment with out employing a flexible sealingmember'externally of the nozzle 57, such as the top web 61a of retainer59, to seal closed the suction nozzle 57.

Although in the specific application herein illustrated, a single aircirculating fan as an independent device spaced from the bank of filterunits at another location in the air flow path is employed to effect airmovement through all'of the filter units in the bank, a fan unit may beassociated with each filter unit module if desired. Such an associationof a fan with each filter unit module may be particularly desirablewhere filter units are to 'be installed over air inlets to individualair flow ducts or in building wall openings for exhausting air to theexterior of a building or in hood assemblies over individual machinesfor reducing the amount of airborne lint in the vicinity of the machine.Where an assembly of a fan and filter unit module is desirable a fan canbe conveniently assembled to the filter unit by providing a fan motorand supporting wire cage on a carrier plate having planiform flanges orrim portions which lap over and may be bolted to the surface of the base20, the carrier plate, for example, having a central opening for the fanblades bounded by a circular flange concentric with the hole 22 in thefilter base 20 and integral with the carrier plate to which the cage issecured to support the fan motor and blades within the central opening.

While but two preferred examples of the present invention have beenparticularly shown and described, it is apparent that variousmodifications may be made therein within the spirit and scope of theinvention, and it is desired, therefore, that only such limitations beplaced on the invention as are imposed by the prior art and set forth inthe appended claims.

What is claimed is:

1. Apparatus for filtering solids from a fluid stream containing thesolids comprising a fluid pervious drum member having a fluid perviouscylindrical filtering wall located in the fluid stream for passage ofthe fluid along radially inwardly directed flow paths therethrough, theoutwardly facing surface of said filtering wall being the upstreamsurface thereof relative to said flow paths, means for establishingpressure conditions within said drum to produce flow of said fluid alongsaid radially inwardly directed flow paths through said wall withaccumulation of said solids on the upstream surface thereof, anelongated penumatic stripper tube spanning the axial length of said wallextending parallel to said members axis radially outwardly of said Wallhaving an intake nozzle immediately adjacent said upstream surfacefacing radially inwardly toward the wall and spanning the axial lengththereof, means for periodically sweeping said stripper tube through asingle revolution cycle along the circumference of the wall from aselected rest position to said rest position, means for applying suctionto said stripper tube to produce suction currents immediately externallyof said suction nozzle during sweeping movement thereof to pneumaticallywithdraw the accumulated solids from the whole working area of saidupstream surface through said nozzle into said stripper tube during eachsingle revolution cycle, and means at said rest position for closingsaid suction nozzle to terminate said suction currents during the periodsaid stripper tube registers with said rest position.

2. Apparatus as defined in claim 1, wherein said means for terminatingsaid suction currents comprises a re siliently deformable sealing stripelement supported on said filtering wall at said rest position having aportion extending the length of said nozzle located sufficiently closeto said nozzle when the latter occupies said rest position to beresiliently deformed by the suction current of said nozzle into sealingengagement therewith to hold the same in closed condition.

3. Apparatus as defined in claim 1, wherein said means for terminatingsaid suction currents comprises valve means activated in coordinatedrelation to the position of said stripper tube for discontinuingapplication of suction to the stripper tube when the latter registerswith said rest position.

4. In a filtering apparatus, the combination recited in claim 1, whereinsaid means for sweeping said stripper tube includes a rectilinearlyreciprocative drive yoke, a pneumatic cylinder supported at a stationaryposition adjacent said axis having a reciprocative piston and pistonrods connected to said drive yoke, said stripper tube having asupporting arm including a radial section and a portion aligned withsaid axis, cable means fixed to said drive yoke and trained about saidportion of said supporting arm aligned with said axis for rotating saidstripper tube and supporting arm about said axis responsive toreciprocative movement of said drive yoke and piston rods, and means forselectively valving fluid under pressure to said cylinder to producemovement of the piston and piston rods in either of two oppositedirections.

5. Apparatus as defined in claim 1, wherein said means for periodicallysweeping said stripper tube includes drive means, a controlled source ofenergy for activating said drive means, main conduit means for normallydirecting energy from said source to said drive means to activate thedrive means to sweep said stripper tube through its cycle when thesource is conditioned to supply energy, branch conduit means connectedto said main conduit means for connection to an external device, andmeans responsive to conditions denoting attainment by said stripper tubeof a selected end position in its cycle to automatically direct theenergy from said source to said branch conduit means.

6. Apparatus for removing lint from lint-laden air comprising acylindrical fluid pervious wall means for supporting a cylindrical lintfiltering web disposed in out wardly surrounded relation by thelint-laden air concentric to a reference axis to intercept thelint-laden air, means for drawing the air outwardly surrounding said webalong radially inwardly directed paths therethrough to accumulate linton the outwardly facing surface thereof, an elongated pneumatic strippertube extending parallel to said axis radially outwardly of said webhaving an elongated intake nozzle immediately adjacent said outwardlyfacing surface of the web facing radially inwardly toward the wall andspanning the axial length thereof, means for periodically sweeping saidstripper tube through an arcuate stroke along the circumference of theweb concentric with said reference axis from a selected rest position tosaid rest position, means for applying suction to said stripper tubeduring sweeping movement thereof to produce suction currents immediatelyexternally of said suction nozzle concurrently along the whole axiallength of the web for pneumatically Withdrawing accumulated lint fromsaid outwardly facing surface of said web through said nozzle into saidstripper tube, and means at said rest position activated by said suctioncurrents when said stripper tube registers with said rest position toclose said nozzle along the length thereof and terminate said suctioncurrents during the period said stripper tube occupies said restposition.

7. Apparatus for removing lint from lint-laden air comprising acylindrical fluid pervious wall means for supporting a cylindrical lintfiltering web disposed in outwardly surrounded relation to the lintladen air concentric ;to a reference axis to intercept the lint-ladenair, means for drawing the air outwardly surrounding said web alongradially inwardly directed paths therethrough to accumulate lint on theoutwardly facing surface thereof, an imperforate circular wallperipherally jointed to said screen wall at one end thereof and disposedperpendicular to said axis, an elongated pneumatic stripper tubeextending parallel to said axis radially outwardly of said web having anelongated intake nozzle immediately adjacent the outwardly facingsurface of the web facing radially inwardly toward the wall and spanningthe axial length thereof, a

radial suction conduit arm supporting said stripper tube stream surfaceof said web through sad nozzle into said stripper tube during eachsingle revolution cycle, and means at said rest position activated bysaid suction currents when said stripper tube registers with said restposi-' tion to close said nozzle along the length thereof and terminatesaid suction currents during the period said stripper tube occupies saidrest position. 7

References Cited by the Examiner UNITED STATES PATENTS 996,860 7/19112,204,928 6/1940 Culver 210-404 2,406,931 9/ 1946 Troxler -294 72,534,171 12/1950 Kirby 55-294 2,765,048 10/1956 Hersey 55294 2,980,2074/1961 Allen 55302 7 3,000,507 9/1961 Young 55 302 3,014,463 12/1961Krohm' 92-437 3,147,098 9/1964 Honan et al 55294 3,166,391 1/1965 Keser55-294 3,169,038 2/1965 Pendleton -3--- 55 294 3,197,944 8/1965 Westerenet al 55--179 P 3,204,393 9/1965 Eklund .Q 55 -467- r 3,243,940 4/1966Larson 55-302 FOREIGN V PATENTS 343,085

2/ 1931 Great Britain.

HARRY B. THORNTON, Primary Examiner.

B. NOZICK, Assistant Examiner.

Kestner s5-294'

1. APPARATUS FOR FILTERING SOLIDS FROM A FLUID STREAM CONTAINING THESOLIDS COMPRISING A FLUID PERVIOUS DRUM MEMBER HAVING A FLUID PERVIOUSCYLINDRICAL FILTERING WALL LOCATED IN THE FLUID STREAM FOR PASSAGE OFTHE FLUID ALONG RADIALLY INWARDLY DIRECTED FLOW PATHS THERETHROUGH, THEOUTWARDLY FACING SURFACE OF SAID FILTERING WALL BEING THE UPSTREAMSURFACE THEREOF RELATIVE TO SAID FLOW PATHS, MEANS FOR ESTABLISHINGPRESSURE CONDITIONS WITHIN SAID DRUM TO PRODUCE FLOW OF SAID FLUID ALONGSAID RADIALLY INWARDLY DIRECTED FLOW PATHS THROUGH SAID WALL WITHACCUMULATION OF SAID SOLIDS ON THE UPSTREAM SURFACE THEREOF, ANELONGATED PNEUMATIC STRIPPER TUBE SPANNING THE AXIAL LENGTH OF SAID WALLEXTENDING PARALLEL TO SAID MEMBER''S AXIS RADIALLY OUTWARDLY OF SAIDWALL HAVING AN INTAKE NOZZLE IMMEDIATELY ADJACENT SAID UPSTREAM SURFACEFACING RADIALLY INWARDLY TOWARD THE WALL AND SPANNING THE AXIAL LENGTHTHEREOF, MEANS FOR PERIODICALLY SWEEPING SAID STRIPPER TUBE THROUGH ASINGLE REVOLUTION CYCLE ALONG THE CIRCUMFERENCE OF THE WALL FROM ASELECTED REST POSITION TO SAID REST POSITION, MEANS FOR APPLYING SUCTIONTO SAID STRIPPER TUBE TO PRODUCE SUCTION CURRENTS IMMEDIATELY EXTERNALLYOF SAID SUCTION NOZZLE DURING SWEEPING MOVEMENT THEREOF TO PNEUMATICALLYWITHDRAW THE ACCUMULATED SOLIDS FROM THE WHOLE WORKING AREA OF SAIDUPSTREAM SURFACE THROUGH SAID NOZZLE INTO SAID STRIPPER TUBE DURING EACHSINGLE REVOLUTION CYCLE, AND MEANS AT SAID REST POSITION FOR CLOSINGSAID SUCTION NOZZLE TO TERMINATE SAID SUCTION CURRENTS DURING THE PERIODSAID STRIPPER TUBE REGISTERS WITH SAID REST POSITION.